Method of operating an internal combustion engine



April 10, 1956 B. REYNOLDS 2,741,230

METHOD OF OPERATING AN INTERNAL COMBUSTION ENGINE 2 Sheets-Sheet 1 FiledJuly 14, 1952 FIG].

CCUM- ULATOR TA NK lGH CE TANE INVEN TOR. BLAKE REYNOLDS AC C UMULA TORTANK 46 i k HIGH CETANE FUEL 42 AC C UMULA TOR TANK 66 LOW GRADE FUEL AT TOPNE V April 10, 1956 B. REYNOLDS METHOD OF OPERATING AN INTERNALCOMBUSTION ENGINE Filed July 14, 1952 FIG. 3.

2 Sheets-Sheet 2 IN VEN TOR. BLAKE REYNOLDS 4 T TOPNE V United StatesPatent '0 ME O OF PE AT AN IN ERVAL OM US ON ENG N Blake Reynolds,Riverside, Comm, assignor to Texaco Development Corporation, New York,N. Y., a cornotation of Delaware Application July 14, 1952, Serial N0.'298, 863

6 Qlairns. (Cl. 123- 32) This invention relates to peciprocatinginternal cornbustion engines and methods of operating them. Moreparticularly, the invention is concerned with methods and apparatus forigniting the fuel in engines of the general YP d ed in Pa n NO- 2 009,Whi h s granted to E. M. Barber on Qcto'oer ll, 1949.

In the improved combustion process with which this invention isconcerned, fluid fuel to be burned the engine is injected during eachcycle of operation of the i e- The nject el i form d i o a pa of bu l mihich s nfin d in n d rec io y a st e m of ox i n as t ave n o a pat h nonta n l ttl o o ap z f 50 th his inc mbu i e- T e ratsh confine the othde by as Qus P o c s f com us o t a lin ay from a flame front at theedge of the patch where the mixture is burned substantially. as fast asit is formed. co mbustion is thus confined to and completed at theleading edge of the patch. Thus, during each cycle of operation of theengine a patch of combustible mixture is progressively or d and nsumedin a localized area o the lind As a result, little or no end gases arepermitted to exist, and even when existent are not egrposed to thepressure and the temperature at which spontaneous ignition Occurs forthe time required to bring about spontaneous ignition. Consequently,ping or "knoc is inhibited even with fuels of low anti-knock value athigh compression ratios. Engines employing such a combustion process aremore efficient than conventional engines, and they will functionsatisfactorily with low grade fuel and with fuels having widelydifferent characteristics.

I have discovered that the improved combustion process described abovecan be achieved in an engine employing glow plug ignition, and that theglow plug can be heated by the combustion of fuel within the cylinder,so that an external source of power for heating the glow plug isunnecessary.

In accordance with my invention, the combustiblen ixture is firstignited in successive cycles by compression, and the heat generated inthe successive compressionignition cycles is utilized to heatthe glowplug to a temperature at which the glow plug will itself ignite thecombustible mixture. Thereafter, the combustible mixture is ignited bythe glow plug during successive cycles of operation of the engine, andsuch ignition continues as long as substantial amounts offuel areinjected into the cylinder.

The glow plug is located so that, after it is sufficiently heated, itignites the combustible mixture so as to provide the flame frontrequired to burn the combustible mixture substantially as fast as it ismade during each cycle of operation, thereby achieving the improvedcombustion P es h. wh c h u smiQ i conce ned- When the engine operatesat low power for a long time, a h n he eagles itl s t e c mbustion withn the cylinder may be insuflicient to maintain glow plus at t empe atu ersq isedito i nite the combu t mixture, and the fuel is then'ignited bycompression until more power is required.

Thus, the ignition automatically changes from compression to glow plugand vice versa, depending upon the amount of power which the engine isrequired to produce.

When the engine operates at low power, it functions essentially as adiesel engine; however, at higher power the combustion process is of theimproved type described above so that the combustion is more efiicientand smoke and diesel knock are eliminated.

The fuel for the engine should have a cetane rating of 40 or more sothat it will ignite by compression when the engine is started and whilethe engine operates at low speed. If desirecha fuel having a high octanerating may be employed to start the engine, and then the engine can beswitched .over to practically any fluid fuel.

The invention is explained with reference to the drawings, in which:

Fig. l is a diagram, partly in vertical section, of an engine forpracticing the invention;

Fig. 2 is a partial plan section of the engine of Fig. 1 showing thelocations of the fuel injection nozzle, the glow p g. n the a ve Fig. 3shows a fuel pump which is suitable for'use in the engine of Fig. l; andI Fig. 4 is a diagram showing an alternative arrangement for the engineshown in Fig. 1.

fuel supply The engine illustratedin Fig. 1 is a fourcycle engine 5 ofthe general type ,described in YU. 53.. Patent No.

7 2,484,009, except that it is provided witha glow plug for ignition, te han a sp rk plu The engine comprises a cylinder 10 provided with acooling jacket 12, and a head 14 provided with cooling channels lfi.Anair inlet port 18in the head opens into the cylinder through a poppetvalve 20 which is provided with a semicircular shroud 20A on one side.

The shroud is so placed that it causes the air to swirl rapidlyaroundthe axis of the cylinder as it is drawn in on the intake stroke,as indicated by the line 21. The swirl thus induced is geared to theengine crankshaft, in that the rate of swirl bears a substantiallyconstant ratio to the R. P. M. of the engine regardless of changes inengine speed. Various ratios may be employed, but for four cycle ng nesof the type here considered, a swirl rate which is about six times theengine speed in R. P. M. is particularly suitable.

An exhaust port 22 in the head opens from the cylinder through aconventional poppet exhaust valve 24. A conventional piston 26 providedwith rings 28 reciprocates in the cylinder. The piston is alsoprovided'with conventional connecting rod and crankshaft (not shown).

A fuel injector nozzle 39 projects into the upper portion of thecylinder above .the top dead center position of the piston and spraysfuel into the swirling air stream therein so as to impregnate alocalized segment of the air stream and form a combustible patch.Preferably the fuel is sprayed from the nozzle 30 in a fan orcone-shaped pattern, and the spray is directed downstream and across theswirling air stream. The rate of injection of the fuel is correlatedwith the velocity of the swirling air and the density of the air so asto impregnate a localized segment of the air stream located at one sideof a diameter of the combustion space.

The nozzle is connected by a pipe 32 to a fuel pump 34. The fuel pump isactuated by a stern or plunger 36, and the plunger is moved by a cam 38which is journaled on a pin 40. The cam is geared to the crank shaft byconventional means (not shown) and makes one complete revolution foreach two revolutions of the crankshaft.

The fuel pump 34 is supplied with fuel from a supply fuel pump 34through a check valve 48;

A glow plug 59, having a portion SilA which extends within the cylinder,is'provided for igniting the combustible mixture within the cylinder.Preferably the glow plug is located about 30 to 60 downstream from theinjector nozzle 39. The glow plug is positioned so that when it isheated to a proper temperature, it serves to ignite the first incrementof the cornbustibie mixtureas soon as it is formed. Thus, a flame isformed at the front of each patch of combustible mixture so that themixture is burned substantially as fast as it is formed. This flamefront tends to travel in a direction counter to the swirl of the airmass and toward the locus of fuel injection. The combustion productsformed in the burning patch travel in the direction of swirl away fromthe flame front, and the flame front is fed by successive increments ofcombustible mixture swirling toward it and formed of fuel injected intothe swirling air. The successive increments of combustible mixture areburned at or near the flame front of the patch substantially as fast asthey are formed during each com bustion period of the engine, theinjection of fuel ceasing assoon as'sufiicient fuel for each powerstroke. has been injected. The combustible patch of mixture is thusconfined on one side by anincombustible layer of the combustion productsswirling away from the patch and on the opposite sideby an incombustiblelayer of air into which no fuel has yet been injected or which does notyet contain enough vaporized fuel to form a combustible mixture.Under'these conditions substantially no end gases are formed, and evenif formed, do not attain the temperature and pressure for a sufficientlength of time 'to result in spontaneous ignition. Consequently ping orknock is inhibited even, with fuels of low anti-knock valueat highcompression ratio'sQ The end 50A of the glow plug 50'is a piece or coilof metal which is heat insulated with respect to the wall of thecylinder, and it is heated by the internal combustion within thecylinder so that an external source of power for heating the plug is notrequired In order as they are formed during successive cycles, whereuponthe glow plug ignites the mixture before compressionignition can occur.

When the engine operates at low power, such as when the engine idles,the combustion within the cylinder is insuflicient to maintain the "lowplug at the temperature required to ignite the combustible mixture, andthe fuel is then ignited by compression until more power is required.Thus, the ignition automatically changes from compression to glowplugand vice versa, depending upon the amount of power which the engine isrequired to produce. a

. Glow plug ignition serves to provide the'fiame front required to burnthe combustible mixture substantially as fast as it is formed andthereby provides a combustion process which is superior to. dieseloperation. Thus, when the engine is operated at higher power, thecombustion is better than that of a conventional diesel engine, andsmoke and knock are eliminated. However, conventional diesel fuel may beemployed and the octane rating of the fuel is relatively unimportant.

Preferably the compression ratio of the engine is relatively low, say 12to 1, so as toavoid heavy diesel construction. However, the compressionratio must be high enough to cause the fuel to be ignited by comeachcycle of operation.

to the fuel injector nozzle. 7 7

provide an exit for the fuel and preclude itsfiow through power, thefuelis injected into the" air stream during about 80 to 90% of the timerequired for the ainto complete-one swirl around the cylinder. Thus, ifthe swirl rate is six times the engine speed in R; P. M., fuel isinjected duringthe period required for the crankshaft to rotateapproximately 7 I For reduced load conditions, the amount of fuel may bereduced by maintaining the rate of injection approximately the same andreducing the relative duration 0 the injection period. 7

The fuel injection is initiated well in advance of top dead center whenthe engine operates at high power. Preferably, the. fuel injectionadvance is adjustable so that the fuel injection is initiated later inthe cycle for reduced load conditions. By way of example, the fuelinjection may be initiated at about 15 before top dead center at lowpower, and it may be advanced uniformly as the power is increased sothat the injection is initiated at about 30 before top dead center athigh power. Fig. 3 shows a fuel pump 34 which is suitable for The fuelpump, has a plunger 51 which reciprocates ina cylinder 52 A rack 53 isprovided for controlling theorientation of the plunger in the cylinderso as to.

control the amount of fuelwhich is injected during Fuel is'admittedthrough an inlet port 54, and it is transmitted. through. avalve 55 Aspill portf56, serves. to

the valve 55 except during the portion of each cycle of operation whenthe port 56 is closed by the plunger. The plunger 51 is provided with aconventional slot 57 and helical surface 58 for controlling the durationof fuel injection in accordance with the orientation of the plunger. Theplunger is also provided with an auxiliary helical surface 59 forcontrolling the injection advance in accordance with the orientation ofthe plunger.

As shown in Fig. 3, the plunger is oriented to provide fuel injectionsof substantially maximum duration as required for high power operation.For low power operation, the amount of fuel which is injected is reachedby moving the rack 53 so as to rotate the plunger counterclockwise asviewed from above. The auxiliary helical surface 59 causes the plungerto close the spill port 56 at a later time during each cycle for lowpower operation; hence the injection advance is controlled in accordancewith the power which the engine is required to produce.

The fuel for the arrangement shown in Fig. 1 should have a high cetanerating, say 40 or more, so that it will ignite by compression when theengine operates at low.

power. I

If desired a fuel havinga high cetane rating may be employed to startthe'engine, and then the engine may be switched over to run onpractically any low grade fuel. Such an arrangement is primarilysuitable for use with engines which must operate at high power over'longperiods of time. a

Fig. 4 shows a suitable fuel supply system for achieving this type ofoperation. This system comprises the same arrangement shown in Fig. lfor supplying the high cetane through a T 70, and valves 72 and 74 areprovided for' turning the fuel on and off in the respective systems.

V I claim:

1. In that method of operation of a reciprocating piston,

5. ter a eeznbq en e .biel ee xie s teas n a mass of compressed swirlingair rotating at high velocity within a combustion space of a cylinder ofsaid engine, injecting fuel into said compressed swirling air so as toimpregnate substantially uniformly with fuel a localized segment of saidswirling air as it rotates past'the locus of fuel injection, promptlyigniting the first increment of injected fuel at a point near said locusof fuel injection substantially as soon as a combustible fuel vapor-airmixture has formed therefrom to establish a flame front traveling in thedirection opposite that of said swirling air, the resultingincombustible combustion products rotating away from said flame front asfresh compressed air rotates toward said flame front, whereby thetraveling flame front is confined on its rear side by a layer of saidincombustible combustion products and on its front side by a layer ofincombustible air, and continuing the injection of fuel into a localizedportion of said fresh compressed air immediately in advance of saidtraveling flame front to form progressively additional combustible fuelvapor-air mixtures which are immediately ignited by said traveling flamefront and burned substantially as rapidly as formed while maintainingsaid flame front confined between incombustible layers, the improvementwhich comprises the ignition of said first increment of injected fuel,as soon as a combustible mixture has formed therefrom, by compressionwhen said engine operates at loW power, and when said engine operates athigh power, the ignition being effected by a solid member disposed atthe mixture locus and heated by the combustion of fuel within saidcombustion space, said injected fuel having compression ignitioncharacteristics favorable for easy starting and operation at low power,and comprising a low grade fuel for operation at high power.

2. In that method of operating a reciprocating piston,

internal combustion engine which comprises forming a mass of compressedswirling air rotating at a substantially constant rate with respect tothe speed of said engine within a combustion space of a cylinder of saidengine, injecting fuel into said mass of compressed swirling air duringeach cycle of operation so as to impregnate substantially uniformly withfuel a localized segment of said swirling air as it rotates past thelocus of fuel injection, promptly igniting the first increment ofinjected fuel at a point near said locus of fuel injection substantiallyas soon as a patch of combustible fuel vapor-air mixture has formedtherefrom to establish a flame front traveling in the direction oppositethat of said swirling air, the resulting incombustible combustionproducts rotating away from said flame front as fresh compressed airrotates toward said flame front, whereby the traveling flame front isconfined on its rear side by a layer of said incombustible combustionproducts and on its front side by a layer of incombustible air, andcontinuing the injection of fuel into a localized portion of said freshcompressed air immediately in advance of said traveling flame front toform progressively additional combustible fuel vapor-air mixtures whichare ignited immediately by said traveling flame front and burnedsubstantially as rapidly as formed, while maintaining said flame frontconfined between incombustible layers, the improvement which comprisesigniting the combustible mixture patch by compression when 'the engineoperates at low power, and when the engine operates at high power,positively igniting on each cycle of operation the first increment ofinjected fuel substantially as soon as a combustible mixture patch isformed therefrom by a solid member disposed at the patch locus in saidcombustion space of a cylinder and heated to an ignition temperaturesolely by the combustion occurring in the cylinder on preceding cycles,said injected fuel having a high octane rating for ease in enginestarting and for engine operation at low power, and comprising a lowgrade fluid fuel for economic engine operation at high power.

3. In the method as set forth in claim 2, said solid 6 a eathe semanticsa. slew sl swhie i is hea d sqte y by he eersbu t' Q w h'n e y nde th fom one type f n ion. t the' th being eu em i nd dep ent 119011 t e e r eof h at n of th s e P s y the combustion.

1n t e matte o P retiQa of a ci o a n p n, nte na nrbuetien en ne as seforth i cl m 2 the si et ea f fue eing i it a e t a d te d m es each Cyle f r 9w newer opera o adva eseem a as earlier t me during a h y le. rh Fe ereraflen, he i niti n. t h h P w b i te by a glow plug which isheated by the combustion of fuel within the cylinder, the shift from onetype of ignition to the other being automatic and dependent upon thedegree that the glow plug is heated by the combustion.

5. In the method of operating a reciprocating piston, internalcombustion engine which comprises forming a mass of compressed swirlingair rotating at a controlled rate with respect to the speed of theengine within a combustion space of a cylinder of said engine, injectingfuel into said compressed swirling air so as to impregnate substantiallyuniformly with fuel a localized segment of said swirling air as itrotates past the locus of fuel injection, promptly igniting the firstincrement of injected fuel at a point near said locus of fuel injectionsubstantially as soon as a patch of combustible fuel vapor-air mixturehas formed therefrom to establish a flame front travelingin thedirection opposite that of said swirling air, the resultingincombustible combustion products rotating away from said flame front asfresh compressed air rotates toward said flame front, whereby thetraveling flame front is confined on its rear side by a layer of saidincombustible combustion products and on its front side by a layer ofincombustible air, and continuing the injection of fuel into a localizedportion of said fresh compressed air immediately in advance of saidtraveling flame front to form progressively additional patches ofcombustible fuel vaporair mixtures which are ignited immediately by saidtraveling flame front and burned substantially as rapidly as formed,while maintaining said flame front confined between incombustiblelayers, the improvement which comprises igniting by compression saidfirst increment of injected fuel as soon as said patch of combustiblemixture has formed therefrom, when said engine operates at low power andthe amount of fuel injected in successive engine cycles is relativelysmall, and igniting said first increment of injected fuel in the patchof combustible mixture in successive cycles by a heated solid memberdisposed at the locus of said last mentioned patch when the amount offuel injected in the later successive cycle is relatively large, andheating the solid member to ignition temperature solely with the heatgenerated by the combustion of fuel within said combustion space, thefuel injected for engine operation at low power having a high octanerating for ease in compression ignition, and the fuel injected inrelatively large amounts being a low grade fluid fuel for economicaloperation.

6. The method of operation of a reciprocating piston internal combustionengine comprising the formation of a mass of compressed swirling airrotating at high velocity within a combustion space of said engine, theinjection of fuel into said mass of compressed swirling air toimpregnate with fuel substantially uniformly a localized segment of saidcompressed swirling air as it rotates past the locus of fuel injection,the ignition of the first increment of injected fuel adjacent said locusof fuel injection and substantially as soonas a combustible fuelvapor-air mixture has formed therefrom to establish a flame fronttraveling in the direction opposite that of said compressed swirling airwith the resulting combustion products rotating away from said flamefront as fresh compressed swirling air rotates toward said flame front,and the continuation of the injection of fuel into localized portions ofsaid fresh compressed swirling air immediately in advance of saidtraveling flame front to progressively form additional combustible fuelvapor-airmixtures which are imme-vdiately'ignited by said travelingflame front and burned substantially as rapidly as formed, the ignitionof said first increment of injected fuel being accomplished bycompression when said engine operates at low power, said injected fuelhaving a relatively 'high cetane rating for ease of compressionignition, and'when the engine operates at high power, the ignition beingelfected positively by a i V solid member disposed at the mixture locusand heated by sarily having easy compression ignition starting charac-,teristics. 7

References Cited in the file of this patent V UNITED STATES PATENTS V1,578,825 Hoaglin Mar. 30, 1926 2,018,727 Kibbe Oct. 29, 1935 2,456,080I Wu Pe Dec. 14, 1948 2,484,009 Barber .4 Oct. 11, 1949

1. IN THAT METHOD OF OPERATION OF A RECIPROCATING PISTON, INTERNALCOMBUSTION ENGINE WHICH COMPRISES FORMING A MASS OF COMPRESSED SWIRLINGAIR ROTATING AT HIGH VELOCITY WITHIN A COMBUSTION SPACE OF A CYLINDER OFSAID ENGINE, INJECTING FUEL INTO SAID COMPRESSED SWIRLING AIR SO AS TOIMPREGNATE SUBSTANTIALLY UNIFORMLY WITH FUEL A LOCALIZED SEGMENT OF SAIDSWIRLING AIR AS IT ROTATES PAST THE LOCUS OF FUEL INJECTION, PROMPTLYIGNITING THE FIRST INCREMENT OF INJECTED FUEL AT A POINT NEAR SAID LOCUSOF FUEL INJECTION SUBSTANTIALLY AS SOON AS A COMBUSTIBLE FUEL VAPOR-AIRMIXTURE HAS FORMED THEREFROM TO ESTABLISH A FLAME FRONT TRAVELING IN THEDIRECTION OPPOSITE THAT OF SAID SWIRLING AIR, THE RESULTINGINCOMBUSTIBLE COMBUSTION PRODUCTS ROTATING AWAY FROM SAID FLAME FRONT ASFRESH COMPRESSED AIR ROTATES TOWARD SAID FLAME FRONT, WHEREBY THETRAVELING FLAME FRONT IS CONFINED ON ITS REAR SIDE BY A LAYER OF SAIDINCOMBUSTIBLE COMBUSTION PRODUCTS AND ON ITS FRONT SIDE BY A LAYER OFINCOMBUSTIBLE AIR, AND CONTINUING THE INJECTION OF FUEL INTO A LOCALIZEDPORTION OF SAID FRESH COMPRESSED AIR IMMEDIATELY IN ADVANCE OF SAIDTRAVELING FLAME FRONT TO FORM PROGRESSIVELY ADDITIONAL COMBUSTIBLE FUELVAPOR-AIR MIXTURE WHICH ARE IMMEDIATELY IGNITED BY SAID TRAVELING FLAMEFRONT AND BURNED SUBSTANTIALLY AS RAPIDLY AS FORMED WHILE MAINTAININGSAID FLAME FRONT CONFINED BETWEEN INCOMBUSTIBLE LAYERS, THE IMPROVEMENTWHICH COMPRISES THE IGNITION OF SAID FIRST INCREMENT OF INJECTED FUEL,AS SOON AS A COMBUSTIBLE MIXTURE HAS FORMED THEREFROM, BY COMPRESSIONWHEN SAID ENGINE OPERATES AT LOW POWER, AND WHEN SAID ENGINE OPERATES ATHIGH POWER, THE IGNITION BEING EFFECTED BY A SOLID MEMBER DISPOSED ATTHE MIXTURE LOCUS AND HEATED BY THE COMBUSTION OF FUEL WITHIN SAIDCOMBUSTION SPACE, SAID INJECTED FUEL HAVING COMPRESSION IGNITIONCHARACTERISTICS FAVORABLE FOR EASY STARTING AND OPERATION AT LOW POWER,AND COMPRISING A LOW GRADE FUEL FOR OPERATION AT HIGH POWER.